1. Field of the Invention
The present invention relates generally to a pressure detector, and more particularly to a pressure detector configured to detect whether the pressure detector receives a predetermined pressure or higher. The present invention is suitable, for example, for a water pressure detector configured to detect whether a cellular phone is placed in a water depth deeper than 2 m.
2. Description of the Related Art
Due to the spread of a portable information apparatus, its environmental guarantee becomes important. For this purpose, a means for easily and less expensively detecting whether the apparatus is placed in the guaranteed environment is required. A pressure is one of the environments to be guaranteed. For example, some cellular phones guarantee the environment resistance down to a predetermined water depth, such as a water depth of 2 m. This is a manufacture's guarantee that the cellular phone even when soaked in water by mistake does not break in the guaranteed environmental range. If the apparatus cannot be proof against the environment in the guaranteed range, a manufacturer needs to repair the cellular phone for nothing.
Prior art include Japanese Patent Laid-Open Nos. 2006-17719, 2001-116637, and 2002-181228.
When a cellular phone is broken due to a submersion, the manufacture cannot conventionally easily determine whether the cellular phone was sunk more deeply than the guaranteed range, or the cellular phone could not be proof against the water depth in the guaranteed range. The contact between the water and the cellular phone needs to be allowed in the water depth in the guaranteed range. It is thus insufficient to simply provide a medium configured to chemically detect the water to the cellular phone. There is proposed no small and less expensive water pressure detector for the conventional waterproof portable information apparatus. Of course, this problem is true of other portable information apparatuses other than the cellular phone, such as a personal digital assistant (“PDA”), a laptop personal computer (“PC”), a watch, a calculator, a game machine, an audio visual apparatus, and a storage unit.